The invention relates to novel, improved correction fluid compositions. More precisely, this invention relates to novel, improved correction fluid compositions which have reduced potential for adverse effects on the environment and on health.
Correction fluid compositions (or correction fluids) for correcting handwritten, typewritten or photocopy markings on papers are known products of commerce and their performance characteristics are well defined. Essential performance characteristics include the ability to provide a film or coalesced residue on drying which can both effectively cover erroneous markings on a paper surface and receive a corrected marking. Preferably, the film covering the marking should be strongly bonded to the paper surface and should also be sufficiently flexible so that the film will not be removed under normal conditions of handling. Additionally, the correction fluid should not interact with the marking to cause excessive discoloration of the resulting film (bleeding). Another important performance characteristic involve the drying rate of the composition which should be as rapid as possible so that corrections can be made relatively quickly. Normally, commercial correction fluids form films which are sufficiently dry to receive a corrected marking in about 30-40 seconds. Other desired performance characteristics include good storage stability coupled with flow and viscosity characteristics which permit easy and even application of the fluid. Details relating to known correction fluids can be found in U.S. Pat. Nos. 3,276,870, 3,674,729; 3,997,498; 4,165,988 and 4,654,081.
As evidenced by the above-listed Patents, halogenated hydrocarbons have been the solvents of choice for correction fluid compositions. Halogenated hydrocarbon solvents presents special advantages primarily because they have evaporation rates which provide correction fluids which can dry rapidly and completely. Additionally, they do not interact with typewritten markings to cause unacceptable bleeding. Also, they can effectively dissolve those film forming polymeric materials which provide durable but flexible films without causing excessive cockling or distortion of paper surfaces. Despite their recognized advantages when used as correction fluid solvents, the use of halogenated hydrocarbon solvents has become a matter of increased concern primarily because of their adverse effect on the environment (stratospheric ozone depletion) and also because of their potential adverse effect on health through solvent abuse. Accordingly, the elimination of halogenated hydrocarbon solvents from correction fluids has become a primary objective for the art and significant efforts have been directed to the development of correction fluids free of halogenated hydrocarbon solvents.
Commercially available halogenated hydrocarbon-free correction fluids developed by the art have not proved to be completely satisfactory substitutes for correction fluids based on halogenated hydrocarbon solvents. Actually, only a relatively few non-halogenated hydrocarbon solvents have the desired combination of performance characteristics needed to qualify for use as correction fluid solvents. For example, heptane or cyclohexane and substituted derivatives thereof provide acceptable non-bleeding performance characteristics coupled with the capability to dissolve polymeric materials which provide the desired durable but flexible films. Moreover, non-halogenated hydrocarbon solvents are not entirely free of adverse effects on the environment and/or on health. Aqueous based correction fluids have also been developed and such fluids do not present any significant threat to the environment or to health. However, they can interact with aqueous based ink markings to cause unwanted bleeding and they also tend to cockle the surface of the paper carrying the marking. Accordingly, a need remains for the development of a halogenated hydrocarbon-free correction fluid which provides a combination of performance characteristics substantially similar to those provided by correction fluids based on halogenated hydrocarbon solvents. This invention is addressed to that need and provides an effective response to the need.